The present invention relates to a core having earth contacting.
More particularly, it relates to a coil having an iron core, in particular an ignition coil consisting of a primary and secondary winding which are inductively coupled by an iron core.
Such an iron core normally consists of a multiplicity of individual thin laminations which are, for example, punched, insulated by varnishing and subsequently packed one above another to form a core stack. During stacking, the individual laminations are, for example, riveted or welded to one another, so that the laminations are electrically interconnected. These core stacks are electrically connected to earth potential, which hitherto has been performed by means of a screw and toothed disc when mounting the core stack on a holder. However, effective earth contacting is not always provided in this operation, for example because of inadequate removal of insulating varnish.
Another possibility is to press a metallic sleeve into recesses or holes in the core stack. During this pressing-in process, the insulating layer at the points of contact--inner wall of the bores of the core stack and outer wall of the sleeve--is at least partially removed, thus producing the possibility of earth contacting by means of this sleeve. The core stack is mounted on a holder by screwing the sleeve, thus simultaneously producing a conductive earth connection. This earth contacting uses a relatively large quantity of material and requires a plurality of steps in the production. This method of earth contacting is not economic enough on the way to an ever more cost effective production.